/Engine/Source/Runtime/Core/Public/Containers/UnrealString.h
Appends otherFStringOutputDeviceCountLinesobject to this one.
virtual [FStringOutputDeviceCountLines](API\Runtime\Core\Containers\FStringOutputDeviceCountLines) & operator+= ( const [FStringOutputDeviceCountLines](API\Runtime\Core\Containers\FStringOutputDeviceCountLines) & Other )